Fair Value Information - Assets and Liabilities Measured at Fair Value on Non-Recurring Basis (Detail) - Fair Value on Non-Recurring Basis [Member] - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Description of assets
Total assets	$ 589	$ 2,846
Other real estate owned [Member]
Description of assets
Total assets	162	0
Loans, Excluding PCI Loans [Member] | Commercial and industrial [Member]
Description of assets
Total assets	22	771
Loans, Excluding PCI Loans [Member] | Small Business Administration [Member]
Description of assets
Total assets	12	296
Loans, Excluding PCI Loans [Member] | Commercial real estate [Member]
Description of assets
Total assets	0	271
Loans, Excluding PCI Loans [Member] | Construction [Member]
Description of assets
Total assets	24	0
Loans, Excluding PCI Loans [Member] | SFR mortgage [Member]
Description of assets
Total assets	292	0
Loans, Excluding PCI Loans [Member] | Dairy & livestock and agribusiness [Member]
Description of assets
Total assets	0	1,061
Loans, Excluding PCI Loans [Member] | Consumer and other loans [Member]
Description of assets
Total assets	77	447
Level 1 [Member]
Description of assets
Total assets	0	0
Level 1 [Member] | Other real estate owned [Member]
Description of assets
Total assets	0	0
Level 1 [Member] | Loans, Excluding PCI Loans [Member] | Commercial and industrial [Member]
Description of assets
Total assets	0	0
Level 1 [Member] | Loans, Excluding PCI Loans [Member] | Small Business Administration [Member]
Description of assets
Total assets	0	0
Level 1 [Member] | Loans, Excluding PCI Loans [Member] | Commercial real estate [Member]
Description of assets
Total assets	0	0
Level 1 [Member] | Loans, Excluding PCI Loans [Member] | Construction [Member]
Description of assets
Total assets	0	0
Level 1 [Member] | Loans, Excluding PCI Loans [Member] | SFR mortgage [Member]
Description of assets
Total assets	0	0
Level 1 [Member] | Loans, Excluding PCI Loans [Member] | Dairy & livestock and agribusiness [Member]
Description of assets
Total assets	0	0
Level 1 [Member] | Loans, Excluding PCI Loans [Member] | Consumer and other loans [Member]
Description of assets
Total assets	0	0
Level 2 [Member]
Description of assets
Total assets	0	0
Level 2 [Member] | Other real estate owned [Member]
Description of assets
Total assets	0	0
Level 2 [Member] | Loans, Excluding PCI Loans [Member] | Commercial and industrial [Member]
Description of assets
Total assets	0	0
Level 2 [Member] | Loans, Excluding PCI Loans [Member] | Small Business Administration [Member]
Description of assets
Total assets	0	0
Level 2 [Member] | Loans, Excluding PCI Loans [Member] | Commercial real estate [Member]
Description of assets
Total assets	0	0
Level 2 [Member] | Loans, Excluding PCI Loans [Member] | Construction [Member]
Description of assets
Total assets	0	0
Level 2 [Member] | Loans, Excluding PCI Loans [Member] | SFR mortgage [Member]
Description of assets
Total assets	0	0
Level 2 [Member] | Loans, Excluding PCI Loans [Member] | Dairy & livestock and agribusiness [Member]
Description of assets
Total assets	0	0
Level 2 [Member] | Loans, Excluding PCI Loans [Member] | Consumer and other loans [Member]
Description of assets
Total assets	0	0
Level 3 [Member]
Description of assets
Total assets	10,290	6,323
Level 3 [Member] | Other real estate owned [Member]
Description of assets
Total assets	948	0
Level 3 [Member] | Loans, Excluding PCI Loans [Member] | Commercial and industrial [Member]
Description of assets
Total assets	37	1,911
Level 3 [Member] | Loans, Excluding PCI Loans [Member] | Small Business Administration [Member]
Description of assets
Total assets	59	1,327
Level 3 [Member] | Loans, Excluding PCI Loans [Member] | Commercial real estate [Member]
Description of assets
Total assets	0	2,500
Level 3 [Member] | Loans, Excluding PCI Loans [Member] | Construction [Member]
Description of assets
Total assets	7,651	0
Level 3 [Member] | Loans, Excluding PCI Loans [Member] | SFR mortgage [Member]
Description of assets
Total assets	1,389	0
Level 3 [Member] | Loans, Excluding PCI Loans [Member] | Dairy & livestock and agribusiness [Member]
Description of assets
Total assets	0	103
Level 3 [Member] | Loans, Excluding PCI Loans [Member] | Consumer and other loans [Member]
Description of assets
Total assets	206	482
Carrying Value [Member]
Description of assets
Total assets	10,290	6,323
Carrying Value [Member] | Other real estate owned [Member]
Description of assets
Total assets	948	0
Carrying Value [Member] | Loans, Excluding PCI Loans [Member] | Commercial and industrial [Member]
Description of assets
Total assets	37	1,911
Carrying Value [Member] | Loans, Excluding PCI Loans [Member] | Small Business Administration [Member]
Description of assets
Total assets	59	1,327
Carrying Value [Member] | Loans, Excluding PCI Loans [Member] | Commercial real estate [Member]
Description of assets
Total assets	0	2,500
Carrying Value [Member] | Loans, Excluding PCI Loans [Member] | Construction [Member]
Description of assets
Total assets	7,651	0
Carrying Value [Member] | Loans, Excluding PCI Loans [Member] | SFR mortgage [Member]
Description of assets
Total assets	1,389	0
Carrying Value [Member] | Loans, Excluding PCI Loans [Member] | Dairy & livestock and agribusiness [Member]
Description of assets
Total assets	0	103
Carrying Value [Member] | Loans, Excluding PCI Loans [Member] | Consumer and other loans [Member]
Description of assets
Total assets	$ 206	$ 482